Analytical entry guidance based on pseudo-aerodynamic profiles

Abstract

An autonomous entry guidance is developed for a hypersonic glide vehicle with high Lift-to-Drag ratio (L/D) based on 3-D analytical glide formulas. To compensate the effects of the Earth's rotation, the pseudo-aerodynamic forces are introduced as the fusions of the aerodynamic forces and inertial forces due to the Earth's rotation. To avoid drastic changes in Angle of Attack (AOA) and bank angle, we carefully forecast the change trends of the inertial forces and then design the pseudo-aerodynamic profiles as inversely proportional functions. Here a complex but useful identity is found and proved theoretically, which helps to simplify the pseudo-aerodynamic profiles without losing accuracy significantly. Subsequently, new 3-D analytical glide formulas are derived for these inversely-proportional profiles and then used to determine the profile parameters and bank reversals. Due to the careful design, the guidance is capable of steering the high-L/D vehicle to any place on the Earth accurately while achieving almost constant commands during the steady glide phase, a major phase of flight. The superior performance of the guidance is verified by the Monte Carlo simulations with challenging disturbances including initial state dispersions, aerodynamic uncertainties, and atmospheric perturbations.